rivt is an extensible, open source Python tool for writing and organizing engineering documents. A rivt document, referred to as a doc, is published as a text, HTML or PDF file from a rivt file. A rivt file is a Python file (.py) that imports the rivtlib Python package and includes rivt markup.
Multiple rivt docs in a rivt folder may be compiled and linked into a rivt report. This site is an example of an HTML rivt report.
An interface for finding public rivt files on GitHub is here and a collection of open source models and calculations on Google Drive, including rivt, is here.